Every day a random hour is selected to be Happy Hour. During Happy Hour a random category is boosted! Solving questions from boosted category yields a tier 3 resource box which is normally given by solving a Yellow Vault and includes 500 Paint instead of 25 for a blue vault. This is a great way to stock up on paint.
Please note that blue paint only drops from blue and green vaults which means happy hour resource boxes can only contain green, yellow, red or purple paint.
The in-game pop-up mentions increased resin drop during Happy Hour, this is wrong and will be fixed in the next update.
All players have the Happy Hour at the same time and the boosted category is also the same for everybody.
No Happy Hour during events, once events are over, Happy Hour returns as normal.